Development of novel solid-state cooling technology that delivers innovation to global warming countermeasures

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K20296
• Project/Area Number (Other): 17H06239 (2017-2019)
• Research Category: Grant-in-Aid for Challenging Research (Pioneering)
• Allocation Type: Multi-year Fund (2020); Single-year Grants (2017-2019)
• Research Field: Inorganic materials chemistry, Energy-related chemistry, and related fields
• Research Institution: Kumamoto University (2020, 2022); The University of Tokyo (2017-2019)
• Principal Investigator: Noguchi Yuji 熊本大学, 大学院先端科学研究部(工), 教授 (60293255)
• Project Period (FY): 2017-06-30 – 2023-03-31
• Keywords: 強誘電体 / 電気熱量効果 / 分極 / 欠陥 / ドメイン / ドメイン壁

Outline of Final Research Achievements

The purpose of this research is to develop solid-state cooling technology that can be used for next-generation cooling equipment. We utilized the interaction between defect dipoles with Cu ion-oxygen vacancy and the spontaneous polarization of ferroelectric barium titanate to control the polarization reversal. The electrocaloric effect in the single-domain state was not significantly different from the pristine sample without polarization reversal, and no temperature change was confirmed. In the multi-domain state, we obtained the world's highest figure of merit measured at room temperature due to de-insertion of ferroelastic domain walls. We have demonstrated that materials design utilizing an interaction between defect dipoles and ferroelectric polarization is effective for enhancing the electrocaloric effect.

Free Research Field

無機材料科学

Academic Significance and Societal Importance of the Research Achievements

強誘電体の自発分極と欠陥複合体の相互作用を巧みに利用することで，ユニポーラーの電圧印加で温度変化0.6 Kを観測した。ここで得られた性能指数は、室温における値としては世界最高性能である。欠陥複合体と自発分極の相互作用を利用した材料設計が、電気熱量効果の増強に有効であることを実証した。
空間反転対称性が破れた極性材料の一つである強誘電体の欠陥を制御して固体冷却が可能であることを実証した本研究は，既存の科学技術の延長線上にはない独創的な機能材料研究である．本成果は，自発分極が非常に大きいZnO、GaNやAlNなどの極性材料にも展開可能であり，固体冷却技術に変革をもたらす成果の創出が期待される。